"[Type]cycling [cost]" means "[Cost], Discard this card: Search your library for a [type] card, reveal it, put it into your hand, then shuffle." This type is usually a subtype (as in "Mountaincycling") but can be any card type, subtype, supertype, or combination thereof (as in "basic landcycling")
The deck can go two different ways, either a pure Assassin kindred deck or one that utilizes cards to give the Assassin creature type to other powerful creatures
While the fast lands arent fetchable like the shock lands and Triomes, they can come into play untapped at no cost, provided that you dont have more than two lands in play
Based on the video games which themselves originally released in the same years 1996 in Japan, then 1998 in the US the Pokemon Trading Game sees players embodying Pokemon Trainers, aiming to knock out six of their opponents Pokemon with their own creatures
If youre able to combine it with more defensive opportunities, or one that will increase your hand in a very short period of time, it can be well worth bringing out, but its unlikely to stay in play for long
youll copy something like Migratory Greathorn or Gemrazer and get two mutate triggers plus a bunch of extra power on board